Corresponding valves have a high-pressure region, a low-pressure region, and a piston-shaped shut-off element disposed in a piston housing between the high-pressure region and the low-pressure region. The end position of this shut-off element must be sealed appropriately because of the great pressure difference, so that the valve securely separates the high-pressure region from the low-pressure region.
A valve of the stated type is known from EP 882 916, in which valve the seat seal is formed by a seal that is disposed in the valve seat of the valve, so that the piston is axially moved against the seat seal when the valve closes, so that the piston lies against the seat seal with its face side. In the open state of the valve, the seat seal is exposed and therefore the flowing medium can flow directly against it at high pressure; consequently, the known seat seal is subject to increased wear and must be replaced frequently.